Question

Thermo: Calorimetry - KE, PE, & Q

SOLIDS Specific heat Material (J/kg.K) Aluminum 921 LIQUIDS Material Specific heat (J/kg.K) Acetone 2150 Brass 402 Benzene 1800 Copper 377 Bromine 470 Glass 840 Ethyl alcohol 2400 Gold 126 Gasoline 2220 Ice 2095 Glycerin 2430 Iron 461 Kerosene 2010 Lead 130 Mercury 140 Nickel 502 Olive oil 1970 2130 Silver 239 Petroleum Styrofoam 1131 Toluene 1720 Zinc 390 Water 4186 Part 1: Bullet A 94 g bullet is fired from a height of 328 m. The initial speed of the bullet is 198 m/s. The bullet eventually comes to rest in a bucket containing 2.1 kg of ethyl alcohol that is at ground level. As a result of bringing the bullet to a stop (any change in PE while in the ethyl alcohol is negligible), how much does the temperature of the ethyl alcohol increase (express the answer in K)? Also determine how fast the bullet is going at impact. Ignore air drag and assume that all of the thermal energy generated goes into heating the ethyl alcohol Impact speed = 205.96 m/s X AT = 0.04 K Part 2: Nail A 0.73 kg hammer strikes a 15 g nickel nail into a wood board. The nail is horizontally aligned and at the moment of impact with the nail, the hammer had a speed of 9.6 m/s. Assume both the hammer and the nail come to a stop and that all of the thermal energy generated goes into heating the nail. Determine how much the temperature of the nail will increase after one hit and how many hits it will take to increase its temperature 90°C. AT after one hit = 4.65 K Minimum number of hits needed to increase the temperature by at least 90°C = 3 x hits

Answer 1

(1) Inpact speed a v2-j² = zah V =279.84328) + (98) V = (213.6 m/s H=MCAT Imr - mar Care AT t +0.094+(213.6) =(2.1) (2400) AT AT=0.425] Kelvin (2) using conservation of nonenten (0.7329.6) - 6-73+0.015) V = 9.4067 mlo H= MLAT t +0.745+ (9.4067)² = 16.015) (502) AT ST= (4.377 k No. of Hits 9 0 [21) Mits 4.377